Low Gradient Aortic Stenosis: Role of Echocardiography

Purpose of Review The purpose of this paper is to review the current role of echocardiography in the evaluation of patients with low gradient severe aortic stenosis (LG severe AS). Recent Findings Discordant grading of AS severity, in which a small aortic valve area coexists with a small gradient, can result in diagnostic and therapeutic dilemmas. Transthoracic, transesophageal, and stress echocardiography play pivotal roles in reconciling the discordance and clarifying AS severity. Three physiologic categories of LG severe AS can be identified (classical low flow (LF) LG AS, paradoxical LF-LG AS, and normal flow LG AS), each with different prognostic and therapeutic implications. Echocardiographic measures of the severity of the valve stenosis, left ventricular function (and functional reserve), and right heart disease provide important prognostic information to assist with patient management. A systematic comprehensive approach using echocardiography is essential in LG severe AS to understand the reason for the discordant hemodynamics, to confirm AS severity, and to guide therapeutic decision-making.